Evaluation of Coronary Ischemia is done in most institutions by either exercise RNA or Exercise Thallium Scanning. A Rigorous comparison of the methods including SPECT Thallium evaluation has not been done. Our purpose is to see if certain groups of patients may benefit more from one study than the other. In addition, we have seen in the first 6 patients that Thallium scanning may detect residual ischemia in peri-infarct areas that is not seen with RNA and it may localize ischemia to better assess specific anatomic vascular insufficiency of the coronary arteries. Finally, patients with severe resting dysfunction can be seen to have extensive ischemia that could be remedial to By-Pass grafting and that RNA may underestimate ischemia in this setting.